The Build Modifier causes the faces of the mesh object to appear or disappear one after the other over time.
By default, faces appear in the order in which they are stored in memory (by default, the order of creation). The face/vertex order can be altered in Edit Mode by selecting Sort Mesh Elements from the operator search menu Spacebar.
使用 Blender 渲染器时，如果网格的材质是光晕而不是标准材质的话，那么逐渐显现的是网格的顶点，而不是面。
- The random seed. Changing this value gives a different "random" order when "Randomize" is checked -- this order is always the same for a given seed/object set.
- The modifier will operate in reverse, essentially allowing it to be used as a "deconstruction" effect. This is useful for making a set of dupli-objects gradually disappear.
The Build Modifier is often useful when needing a way to get a large number of items to progressively appear, without resorting to animating the visibility of each one by one. Examples of this include a mesh containing vertices only, which is used as a duplivert emitter, and has the build modifier on it. Such a setup is a workaround/technique for being able to art-direct some semi-random layout of a collection of objects (i.e. leaves/balls forming a carpet of sorts) when doing so with particles is not desirable (e.g. due to undesirable distribution of items leaving random gaps and overlapping in other places).